Question

我想创建一个函数来保存downloadHandler函数并动态地提供它的详细信息，但我不断收到消息

“找不到''''''''''''''''''''''''''''''''''''''

我的下载功能如下：

downloadPlots <- function(fileName,plotFunction,fileFormat,fileContentType){
if(fileFormat=="pdf"){ #because it doesn't require specification of contentType. Others do
  downloadHandler(
    filename = fileName,
    content = function(file) {          
      pdf(file, pointsize = 12, bg = "white", res = NA)
      FUN <- match.fun(plotFunction) 
      FUN()
      dev.off()
    }
  )
}else{
  downloadHandler(
    filename = fileName,
    content = function(file) {
      if(fileFormat=="png")
        png(file, pointsize = 12, bg = "white", res = NA)
      FUN <- match.fun(plotFunction,descend = TRUE) 
      FUN()
      dev.off()
    },
    contentType = fileContentType
  )
}

}

这就是函数的调用方式

output$histPng <- downloadPlots("histogram.png",histogram(),"png","image/png")

在ui.R中，下载图的代码如下：

downloadButton('histPng','PNG')

Answer 1

我认为问题（没有任何测试）可能是您将绘图函数错误地传递给downloadPlots()。从函数调用中的histogram中删除括号：

output$histPng <- downloadPlots("histogram.png",histogram,"png","image/png")

R Shiny error：找不到模式'function'的对象'plotFunction'

1 个答案: